This invention relates generally to the field of combination filter/dehydrators used in the refrigerant industry for purification of refrigerant gases such as Freon. In particular the invention relates to such devices having an end mounted sight glass for detection of color change in a saturation indicator and specific structural configurations for the filtering/dehydrating material.
In a refrigerant containing system, such as an air conditioner for example, moisture will develop and collect within the system. This moisture is harmful to the system and will cause the system to operate ineffectively. To prevent this, it is well known to include a dehydration device as a component of the system. The dehydrator contains a drying agent which absorbs any moisture present in the system. For example, silica gel is a common drying agent used in dehydrators. However, a problem with the use of drying agents is that they become saturated over time and it is necessary then to replace the saturated material with fresh material.
In some systems, this replacement of the drying agent is performed at intervals determined by time or quantity of gas flow. This is an inexact system, as it may well result in the material being changed either prematurely or belatedly. To improve on this, it is known to incorporate an indicator in the drying agent which will provide a signal when the drying agent is saturated. For example, it is known to incorporate cobalt chloride in the drying material. The cobalt chloride turns from blue to pink as the silica gel becomes saturated and the operator can judge the material replacement need by monitoring this color change. Schulstadt in U.S. Pat. No. 2,579,053 teaches such a dehydrator device. This device, similar in construction to other standard devices, comprises a cylindrical, transparent tube for housing the drying agent. As the color change progresses from one end to the other of the drying agent, the user knows when the time for changing the silica gel is approaching. A major drawback in this construction is that the cobalt blue is incorporated throughout the silica gel and a large transparent cylinder is required.
It is an object of this invention to provide a particular structure for a filter dehydrator housing incorporating a saturation indicator, where only a small amount of indicator is required and only a small sight glass at one end of the housing is needed to monitor the saturation level.
It is a further object of the invention to provide such a housing where the replacement of the filter/dehydrator material is achieved by removable of the end cap containing the sight glass.
It is a further object of this invention to provide such a device where the drying agent is in a compressed and fixed body, such that the body can be given a particular structural shape to improve performance and indicator ability by directing the gas flow over specific pathways.
It is a further object of the invention to provide such structural shapes whereby the gas flow pattern relative to the drying agent and the indicator material is improved.